Separation and recovery of lignin from hydrolysates of lignocellulose with a polymeric adsorbent

- Separation of lignin from hydrolysates of lignocellulose by adsorption was studied.
- Efficient separation was achieved using polystyrene-based XAD-16N adsorbent.
- Adsorbed lignin could be desorbed with 100% desorption ration with 50 wt.% ethanol.
- Lignin with high purity can be produced with the presented adsorption process.
- Applicability of the process on large scale was demonstrated successfully.

Separation and recovery of lignin from monosaccharide rich hydrolysates of lignocellulose by adsorption was investigated. Six polymeric adsorbents were compared by batch equilibrium experiments. XAD-16N was found to be the most efficient. Use of XAD-16N was studied in more detail in a column. A good separation efficiency could be obtained: with 95% monosaccharide recovery yield limit, the lignin removal level was 80%. Organic acids and furans were not adsorbed on XAD-16N. Practically all of the adsorbed lignin could be recovered efficiently with 50 wt.% aqueous ethanol solution. The lignin fraction had 99% purity with respect the other solutes in the hydrolysates. Applicability of the process on large scale was demonstrated successfully by scaling up the process using data obtained with a laboratory scale unit (scale-up factor: 420). A 76% lignin removal (target: 70%) was achieved with higher than 95% monosaccharide recovery yield (target: 95%).